From the site:
Very interesting site, I looked around for quite a while. The interface is black and white and everything you need is easy to see and get to.
Course materials are in audio and text formats. The materials I tested were in MP3 format for audio, and PDF for text. MP3's are labeled "Tapes" in the listings and PDF's are listed as text. Some languages have more course material than others - for example, Spanish has more material than Sinhala.
One of the things I liked as I was going through course material (in the one foreign language I know a little about) is that much of the information is presented in context. There's background and cultural tidbits that make it more lively and interesting than a textbook. On other words, some of the "here's how it's done, and here's why" that I'm always curious about. Go forth, explore, and have fun. :)
FSI Language Courses